Ceiling spots may not be leaks

January 15, 2009|By KEN SHEINKOPF McClatchy-Tribune News Service

Q. I recall you writing something a while ago about spots that look like water leaks on the ceiling that might be caused by insufficient insulation. I think we might have this problem, and I don't remember what you said about fixing it.A. I've heard from a few people over the years who've had problems like this, finding condensation or mildew-looking spots in places on their ceiling in a room. The first thought they have is these are water leaks, but an inspection of the roof can quickly determine if this is the problem. Experts have told me there are usually two problems besides roof leaks that can cause these spots. One does deal with the insulation, since cold air reaching the ceiling when the attic is poorly insulated can result in the moist air condensing on the ceiling. If this is your problem, then adding ceiling insulation, especially near the eaves, can take care of this. The other possible culprit could be water dripping down from the roof, though not from a leak. Moist air can get into a cold attic and form ice crystals on the underside of the roof, a problem called an "ice dam." On a sunny day, the roof will warm up and the higher temperature causes the ice to melt, resulting in water dripping onto the ceiling. Making sure your attic insulation reaches all the way to the exterior wall top plate can keep ice dams from forming. Also have someone inspect the attic to be sure the joints are well-sealed where the wall meets the ceiling, since an exterior wall that is poorly insulated at the top plate can cause problems. So it sounds to me that if the roof isn't leaking, a lack of insulation in the attic could be the cause of these ceiling spots. Ken Sheinkopf is a communications specialist with the American Solar Energy Society (www.ases.org). Send your energy questions to askken@ases.org.